Power and amplifying equipment for distribution of intelligence over wires



Feb. 3, 1925. 1,525,054

- J. F. TooMEY POWER AND AMPLIFYING EQUIPMENT FOR DISTRIBUTION OF INTELLIGENCE OVR WIRES Filed Dec. l, 1923 5 Sheets-Sheet 1 42 Mz'J/z/rmalcmsg X W N V H IN VEN TOR Feb. 3, 1925.

J. F. TooMEY POWER ANDl AMPLIFYING EQUIPMENT FOR DISTRIBUTION OF INTELLIGENCE OVER WIRES Filed Deo. 1,' 1923 3 Sheets-Sheet 2 Q W A TTORNEY Feb 3, 1925- 1,525,054

J. F. TooMl-:Y

POWER AND AMPLIFYING EQUIPMENT FOR DISTRIBUTION 0F INTELLIGENCE OVER WIRES Filed Dec. l, 1923 l 3 Sheets-Sheet 5 @arme/fa? fome E I N VE N TOR W A T TORNE Y Patented Feb. 3, 1925. j

UNITED STATES Vrari-:NT OFFICE..

JOHN F. TOOMEY, OF NEW YORK. N. Y., ASSIGNOR TO AMERICAN TELEPHONE AND TELEGRAIPH COMPANY, A CORPORATION 0F NEW YORK.

:POWER AND AMPLIFYING EQUIPMENT FOR DISTRIBUTION OF INTELLIGENCE OVER l WIRES. i I

Application and Dwember 1. 1923. serieu Noxevvesr To all whom z't may concern.'

Be it known that I, JOHN F. TooMEY, residing at New York, in the county of New York and State of New York, have invent-Y ed certain Improvements in Power and Amplifying Equipment for Distribution o-f Intelligence over Wires, of which the following is a specification.

This invention relates to electrical systems for distributing music, news, information and the like, and more particularly to arrangements for such distribution -over wires. y

In accordance with thepresent invention, it is proposed to arrange a wire distribution system so that trunks will .extend from a main program station to a number of outlying central .offices at which suitable amplifying arrangements maybe provided. From each central ofiice trunks or local lines ,will be extended to points in the vicinity of groups of subscribers, such points being, for example, apartment houses or the like. Additional amplifying means may be arranged at these outlying point-s, and circuits may be extended from such points to the subscribers of the group las, for example, to the various tenants in the apartment house. Suitable sources of power must necessarily be associated withthe amplifying arrangements both at the central stations and at the `outlying stations, such as the apartment houses.

For the most economical working of such a system, the amplifying arrangements at the/central stations and at the local distributing points, such as the apartment houses, should be so arranged that it is unnecessary to provide attendants at either the central offices or the distributing points for ma intaining the apparatus in operative condition. Accordingly, one of the objects of the invention is to provide means for enabling the attendant at the main broadcasting station to control, over the trunks used for distribution, the operation of the power and amplifier equipment at the dist-ant central ,o-f'ces and at the distributingpoints, such as apartment houses, that are involved in the system.

Another object of the'invention is to provide means for automatically switching a reserve generator into the circuit at a central office in case of failure of the regular generator which supplies the power for the amplifiers, etc., at that office.

circuit in case of power Jfailure without switching the spare amplifier. A

Still another object of the invention is to provide remote control circuits which include a signaling arrangement for indicat- .ing to the attendant'at the main station when all of the power apparatus and amplifiers that are associated with a particular circuit are functioning in the proper 1nan. ner. A further object of the invention is to provide an arrangement such that if any of the amplifying or power equipment or other i associated apparatus fails to function t-he failure is indicated to the attendant at the main station by means of a signal which may preferably be associated with an alarm circuit. The operation of this sign-al may also be supplemented by local'alarm circuits at each central office which indicate to the trouble man (orto the attendant, where one is provided at these places) the particular piece of equipment that has failed. v

These objects, as well as other objects of the invention more fully hereinafter appearing, are attained by means of the arrangement set forth in the following` description .and illustrated in the accompanying drawing in'which Figs. 1, 2 and 3, when placed side by side, with Fig. 1 at the right, disclose circuit arrangements vof apparatus at the main broadcasting station, at' a central office :and at -an'outlying distributing point such as a power house, these circuits comprising a preferred embodiment ofthe invention. f

The apparatus at the main program station is shown above and at the right of the dotted line a-a in Fig. 1. y The power equipment for a central office is shown in the lower part of Fig. 1. The regular amplifier and spare amplifier at a central office together with the associated equipment is shownin Fig. 2. The amplifier for an outlying distributing point such as atn'apartment house is illustrated in thev upper part of Fig. t3, and the correspondii'ig power equipment 1s illustrated in the lower part ot' Fig.

The general leatuws ol' the apparatus herein disclosed will first be described, the details of the circuits being made clear in connection with the description ol the operation ol the invention to be given later. lt will be understood that the appaiatus herein disclosed, while intended primarily for a wire distribution system employing voice frequencies is equally capable of use in connection with a' similar system transmitting at carrier l'requencies. l b

Referring to Fig. l, an amplifying set comprising tubes A1 and A2 is provided at the main program statiom'a connection leading from the studio being associated with the input of the amplifier A1. The output ol' the second-stage amplifier A leads through suitable 'jacks .l1 and J2 to bus-oars l() from which branches lead through transl'ormers such as ll, l2, etc., to trunks Tn, Tb, etc., extending to distant central oflices. The trunk Ta extends -to the central office A, a part ofwhose equipment'is illustrated in Fig. 2. Associated with each trunk as, for example, TM is an O. K. signal 13 and an alarm signal lll. catcs when the apparatusis set into operation that all oi' the apparatus at the various central stations and outlying distributing points is 'functioning properly. The latter Isignal indicates trouble at some point. A switch, such as the 'jack .lm common to the various trunks leading to central oflices is provided at the program station yXvi'or setting the circuits into. operation.

At the central olliee A (see Fig. 2) an amplilying set is provided comprising a. first-- stage amplifier An and a push-pull amplilier A4. This amplifying apparatus will normally be included in series with the trunk Tn, but in the event this amplifying arrangement is disabled a spare amplifying set is provided comprising a. first-'stage amplifier A3 and a second-stage push-pull ampliiier A4. Suitable relay arrangements are associated with the amplifiers for automatically switching in the spare amplifierwhen the main amplifier is disabled, as Willbe described later. Similar amplifying apparatus and cont-rol circuits are providedv at the other central oflices (not illustrated).-

In order to provide the energizing currents for the amplifiers at each lcentralv oflice A, power equipment is provided as illustrated at the bottom of Fig. l, the particular powerV apparatus illustrated being located at the central oflice A, for supplying the amplifiers at that ofiice. e uipment comprises a motor generator set BG which may be'operated from a storage The l'ormer signal indi-- j erat'ed from the The power battery, for example, and an alternate motor generator set MG which may be operated from the usual power mains ol' an electric lighting system. l Both ol` these generators are designed to generate the desired plate voltage for the amplifying equipment which, in the case illustrated, may be 350' volts. (.)ne ol' these motor generator outfits may be used for regular operation, and the other setl may be used as a spare. A power switch lh' is provided .for determining which motor generator set will be used l'or regular operation. When the. power switch lS is thrown to its upper position, the motor generator set Mtl lwill be used in the norma-l operation of' the circuit, and when the power switch is thrown to its lower position the motor generator set Mtl will he used in th(I normalv operation.

Suitable switching devices are provided for setting the regular motor generator equipment into operation whenever the main switching 'jack'.h, at the main program station X is operated. When the motor generator is set into operation, it supplies the space current 'to the amplifier at the central oiice A. Suitable switching devices are also provided for switching the alternative motor generator set into the circuit in case trouble develops uponthe 4motor generator set which is' regularly fused. The details of the switching apparatus will be describe-d more fully hereinafter.

The power amplifying equipment at the central oflice A is intended to supply ain-y plified program transmission for a number otoutlying [distributing stations, such'as apartment houses, and for this purpose con-4 ductors 15 lead from the output side of the .amplifying equipment to the bus-bars 16.

From these bus-bars trunks lead in multiple to the various distributing points, such, for example, as the apartment house Il (see Fig. 3). the latter'being connected to the busbar lo through the trunk Th.

At the distributing point, such as the apartment house H, an amplifying equipment is interposed between the trunk Th and the bus-bar 17 to which the various ex* tensionsare connected which lead to the individual subscribers in the apartment house or elsewhere in the neighborhood. This ain- Vplifying equipment comprises a firststage amplifier A5 and asecond-stage push-pull amplifier AG. In order to provide the c'urrent supply i'ory operating the amplifier, whiclris a .power amplifier, a motor generator apparatus MG1. is provided, and the motor of this arrangement is designed to be oppower mains'entering the apartment house or other distributing point. Controlling circuits for starting and'stopping the lamplifier from the broadcastin stat1on are provided, as. described hereinafter.

will be more fully i Further details of the apparatus will be clearffrom a description of thel operation which is as follows:

When the program .is about to start at the studio, the attendant at the main program station X establishes the circuits in their operating condition at the main program station, the outlying central stations and all of the distant distributing points, such as apartment houses, by inserting an idle plug in the jack J3. This operation closes the circuit to battery over thelcontact of the Jack and over conductor 1'8 to the ilaments of the amplifiers A1 and A2 thereby rendering the amplier at the main program station operative. A circuit is also closed from battery over the contact of the jack J3, over the conductor 19, through the marginal relay .20, over the ring side of the trunk Ta leading to the central o'flice A, through the high resistance winding of the relay21 and back over the tip side of the trunk 'la to ground at the midpoint of the secondary of the transformer 11. Similar circuits areclosed by the jack J 3 over all of the other trunks connected to the bus-bars 10. The relay 20, being marginal, is not energized over the circuit including the high resistance Wlnding of the relay 21.

The relay 21, on gized and at its front contact completes a circuit from ground, o-ver the conductor 22, over the conductor 23, through the winding #of the relay 24 to battery; The purpose of the relay 24 is to set into operation the motor generator vapparatus which is arranged to normally supply the amplifiers at the central olice A. Which of the two mot-or generators MG and MG will normally be used is determined by the setting ot the power switch PS.

Assuming that the power switch is thrown to its upper Contact 25, a circuit is closed from round, over the inner front Contact of the re ay 24, over the switch PS, Contact 25, conductor 26, right-hand back contact of relay 27, conductor 28, and. through the winding of relay 29 to battery. Relay 29, upon being energized, completes a circuit over its upper front contact Jfrom ground, over the inner Contact of relay 24, conducto-r 30, upper front contact of relay 29, through the control switch 31, and through the winding of power signal relay 32 t0 battery. Power signal relay 32, upon `being energized, connects the automatic starter magnetic switch 33 into circuit with the power mains 34 leading to the storage battery supply source for operating the motor generato-r MG. The automatic starter magnet 33 is accordingly energized and connects themotor generator set MG to the power mains 34, so that the motor generator no-w starts to operate.

It will be obvious from the circuit that the motor generator MG may be started locally the other hand,is ener-y by .an attendant-upon throwing the switch 31 to its lower position thereby energizing.

the power signal relay 32.

Returning to relay 29, a circuit is closed over its lower frontcontact from ground, over the inner front contact of relay 24, conductor 30, ,lower front Contact of relay- 29 and through the winding of relay 35 to battery.' elay 35, upon being energized, connects the out-put conductors36 ot motor generator MG over its front contacts and through the filter 37 to the power bus-bars 38. i conductor 39 leads from the power bus-bars to point 40, so that when the. motor ,generator MG. reaches its full speed a voltage of about 350 Volts will be supplied to thepoint 4() for energizing the plate circuits of the central olhce amplifiers, as will bedescribed later. As soo-n as the motor generator MG reaches its full speed and generates the proper voltage for the bus-bars 38, the relay 41 is energized and completesV a circuit at its fro-nt contact for the left-hand winding of the relay 42. Relay 42 is then locked up from battery, through its lefthand winding and over its right-hand front contact, over conductor 43, middle left-hand back contact ofrelay ,27, conductor 44, restore key 45, -and* over the outer front contact of relay 24 to ground. Relay 42 pro* duces no circuit translation at this time, its purposebeing to control a trouble signal circuit as will be described later.

In the event the motor generator set MG is to be used as the normal source of power supply, the power switch PS will be thrown into its lowercontact 25 in which case no circuit would be completed for the relay 29 upon the energization of relay 24, since the circuit of the relay 29 would now be open at the right-hand back contact of relay 2T. Consequently when the relay 24 is energized, a circuit is completed Jfor the power signal relay 32 from ground, over the inner front contact of relay 24, conductor 30, upper back contact of relay 29, over the control switch 31', and through the winding of the powerl signal relay 32 to battery. The power signal relay, upon being energized, connects theautomatic starter switch 33 tothe power mains 34. The automatic starter switch 33 is thereby closed and connects the power mains to the motor .of the motor generator apparatus MG thereby setting the apparatus into operation.

A circuit is also completed for the relay 35 Jfrom ground, inner front contact offrelay 24, conductor 30, lower back contact of relay 29, and through the winding of relay 35 to battery. Relay 35 connects the output conductors 36 of the motor generator set MG to the bus-bars 38, and through the filter 37. Consequently the current for suppl'ying the plate circuit 'to the lamplifiers will be generated by the motor generator will be described later.

Mtll As soon as the motor generator MG reachesl its l'ull speed and generaties the (lesired Ivoltage, the relay 4l will be operated with the results previously set l'orlh.

Returning now to the relay 2l. which it will be recalled was energized at the time the plug was inserted in the jack .lg at the main program Istation. it' will be observed that the relay .l closed a eil-enit from ground, over its front eonlaet, over the conductors 22 and 47, and through the winding ol' relay /l-S to battery. .lelay 48, upon heilig energized, closes the lilament eireuit ol' the normal ampli'lw'ing .set as follows: l'rom the 24 rolt battery, over the lelt -hand back contact. vo'l' relay 52. lel't-hand l'ront contact olI relay 45. through the impedance coil and resistanee and thence through the lilarnents of the amplifying arrangements and A, in series to ground.

The lilaments oll theI normal :unpliliers A and A, are now caused to glow, thereby permitting thc space currentto llow. 'l`he space current. for the ainplilier will llow from the point 40 (which is connected to the bus-bars 38 oit the motor generator sel), through in'ipedance coil 555, relay ttt, over the conductor 55, and through the. primary winding i the transformer 5G to the plate of the amplilier. Similarly, the, space eurrent l'or the amplilier A4 flows from the point 40, through the impedance coil 53, winding oi the relay 57, over conductor 58 to the midpoint Ql the primary windings ol the transforn'ier 59, and thence to the plates ol the twol tubes of the amplifier A4.

Relays 54 and 57 are energized by the plate currents and complete a circuit for the right-hand winding oi the relay 49 as 'lollows: from ground, over the back contact ol relay 4G ot' the power equipment (this relay is dcenergized when the` power equipment is normal), over conductor (St), Jront contact of relay 57, front Contact oi relay 54, and through the winding of relay 49 to bat'tely. Relay 49 is energized and is locked up through its right-hand Winding and inne-r ri glit-hand front contact, and over the conductor (S1 and right-hand front contact ol relay 48 to ground. At its righthand trout contact relay 49. prepares the eircuit'- through the low resistance Winding et the relay 2l oi the trunk Tn, this low resistance path being actually completed when the relay 62 is energized in response to the establishment ol the circuits at all of thc apartment house distributing points as When the W resistance shunt path of the relay 21 is completed, a. signal will be given at the main program station as will be hereinafter set forth. i

Returning again to the relay 48, a circuit is completed by the actuation of this relay from ground, over its right-hand front contact and over conductor 63, through winding otl relay (i4 to battery. The relay 64 is thereupon energized and connectsI batterv to the bus-bar 65. Associated with each trunk leading from the bus-bars 'lt is a. relay such -as (Sti, and one terminal ol. each relay ot' this type is eonneeted to the busbar ($5. Consequently when the relay ('14 pulls up, a circuit will he completed i'or'each olf the relays such as tt. lhe circuit of this particular relay is lfrom battery, over the l'ront contact of relay (34, bus-bar (it). winding of relay (36 to the midpoint ol' transl'ormer ($7, over the ring conductor of trunk 'l`. through the high resistance winding oi' relay GH, over the tip conductor ot the trunk 'l`, and through the upper halt' of the secondary winding of transformer 67 to ground.

Relay tl' is marginal and is not energized in series with the high resistance. winding ot the. relay (5S. ltelay tt's attracts its armature. however,- and completes a circuit Jfrom ground. over said armature, over conductor el), conthwtor 7l), through the winding oft' relay 71 to battery. Relay 7l completes a circuit over its le'l"t-hand front contact from ground, through the winding oi' the power signal relay 72 to battery. flower signal relay 72 in turn connects thc winding of the automatic starter magnetic switch 73 to the ponen-mains 74, thereby energizing the automatic starter switch. rlhis switch, when closed by its magnet eoil connects the power mains 74 to the motor element ol the motor `generator set MGP ',lhe motor generator set MGr1 comprises a motor and two generators 76 and 77 respectively. 'lhe generator 76 generates a Vo-ltage o' 35() volts l'or supplying the space current oi the amplifying set at the apartment house or other distributing point. The generator 77, on the other hand, generates approximately 2() volts for supplying the lilament current of the tubes of the amplilier. As soon as the ino-tor generator set attains its full speed, volts Will be appliedto the terminals of the relay 78 which 1s brldged across the generator terminals, and this relay will accordingly be energized to complete a circuit, for the right-hand wmdmg of relay 79. Relay 79 locks up over a circuit from battery, through its left-hand winding, and over its inner lett-hand contact, through the restore key S0 and over the right-lmnd front contact of relay 7l to ground. At its outer left-hand Contact relay 79 prepares the circuit ot' the low resistance shunt Winding of. the relay 68 as will be described later.

The 350 'volt generator 76 of the motor generator set MG1 is connected through a filter 81 to the terminals of the winding of relay 82. This relay is energized When the full voltage of the generator 76 is reached and at its front contact closes a circuit through the right-hand Winding of relay 83. Relay 83, upon being energized, completes a locking circuit from battery, over its lefthand front contact, and over the key'80 vand right-hand front contact of relay 71 to ground. At its outer left-hand front contact relay 83 closes the circuit of the lo-W resistance shunt winding of the relay 68 at another point.

Returning again to relay 68, a circuit is completed from ground, over its front contact, Ciover conductor 69, conductor '84 and through the Winding of relay 85 to battery. Relay 85, upon being energized, closes the filament circuit of the amplifying apparatus A,.,-A6 from the 20 volt terminal of the generatorl 77 over the conductor 86, front contact of relay 85, through a choke coil and resistance and thence through the filaments of the amplifiers A6 and Ar in series to ground. The filaments are thereby caused to glow so that the space current flows through the tubes. The space current is supplied to the plates of the amplifying tubes, over a circuit from the 350 Volt terminal of the generator 76, over conductor 87 to the point 88. From this oint a circuit eX- tends through the Winding of the relay 89 to thel midpoint of the primary windings of the transformer 90 and thence to the plates of the two tubes of the amplifier 86. A circuit also extends from the po-int 88, through the winding of the relay 91, through the primary Winding of the transformer 92 to the plate of the amplifier A5.

As soon as the plate current Hows through the amplifying tubes, the relays 89 and 91 are energized, completing a. circuit from` ground, over the front contacts of said re- -lays in series and through the left-hand winding of' relay 93 to battery. Relay 93, upon being energized, completes a locking circuit from battery, through its right-hand winding and right-hand fro-nt contact and thence over conductors 84 and 69 to ground over the contact of relay 68. The relay 93 at its left-hand front contact prepares a circuit for the relay 94'so that'if either the relay 89 or 91 should be deenergized the circuit for the relay 94 Will be completed.

The relay 94, by means of its contact, exercises control over the circuit of the low resistance Winding of the relay 68 previously referred to. If the amplifiers are in proper Working order When the motor generator set is started in operation, the relay 94 will not be energized, and hence the low resistancel shunt Winding of the relay 68 will have its circuit completed as soon as the relays 79 and 83 are energized, the low resistance.

shunt circuit extending o-ver the back contact of the relay 94 and over the front contacts of the relays 79 and 83 in series. Consequently when the motor generator set is` started into operation and the amplifying equipment is functioning normally, the resistance of the relay 68 will be reduced, thereby causing the marginal relay 66 to be energized.

Similar operations take lace in connection with other trunks leadmg to apartment houses and other distributing points, and if the apparatus associated with the various trunks is functioning normally, relays corresponding to 66 will be energized for each trunk. A circuit will then vbe completed from ground, over the front contact of the series with theouter right-hand contact of the relay 49, and consequently when both of these relays have been energized (which can only take place When all of the apparatus is functioning normally), the circuit of the low resistance shunt winding will be completed, thereby reducing the resistance in series with the marginal relay 20. Marginal relay 20 is thereupon energized, and at its front contact completes a circuit from ground through the Winding of relay 96, conductor 19 and the Contact of the J, to battery. The relay 96 upon being energized completes a circuit for the O. K. signa-l lamp 13 from battery, through said lamp, .over the right-hand front contact of relay 96, over the lleft-hand back contact of the relay 97 to ground. This indicates to the attendant at the main program stan tion X that all of the equipment is in propel' order and functioning normally.

We will non1 consider what takes place in the event tro-uble develops in the'equipment at the localdistributing point such as an apartment house. If the 2O Volt generator 77 should not function properly, the relay 78 Will be deenergized and a. circuit Will be completed from ground over its back contact andv over the front contact of relay 79 to actuate a local signal 98. The current supply for the filaments of the amplifiers A6 and A5 Will also be interrupted or reduced if the generator 77 is not functioning properly, thereby either interrupting or reducing the plate current of these tubes. This will cause the relays 89 and 91 to fall off and complete a circuit from ground, over the back contacts of relay 89, over the lefthand front contact of relay 93, through the Winding of relay 94 to battery. Relay 94 tubesY of the amplifiers An or A will also be interrupted Yor reduced by "trouble on the generator 76 so that the relays 89 and 91 will fall off, completing the circult of the relay 94 and thereby opening the 10W resistance shunt of relay'68 yas above described.

Similarly, if the motor should develop trouble, or if the conductors of the power mains should be interrupted, relays 78 and 82 would both berdeenergized to ac-tuate the signal 98,7and the filament space current of the amplifiers A5 and A(x would cease Yflow-l ing so that the relay 94 would be energized over the back contact otY relay 89 to open the low resistance shunt of the relay 68.

If a filamcnt'ot one of the tubes 'et the amplifying apparatus A5 and A(x should burn out, the filaments of all of the tubes would cease toglow, as they are connected in series. Accordingly, the space currents would be interrupted Yand the relays 89 land 91 be deenergized, thereby completing' the circuit .if thelrelay 94 to open the low resistance shunt Vot relay 68. If, for any reason, the space current shouldcease to flow through the amplifier A5, the relay 91 would be deencrgized, therebycomplet-ing the circuit from ground, over the front contact of relay 85, over the back contact of relay 91 and over the left-hand front contact of relay 93, through the Winding of the relay 94 to battery. The relay 94 would therefore open the lou7 resistance shunt of the relay 6811s before. Similarly, if the space current ot the amplifier 86 should cease lowing-to`r any reason, the relay 89 will be deenergizcd to complete the circuit of' the rela-y 94 and interrupt the shunt of the 'relay 68.

Obviously any trouble'in the nmotor generator setror inl theamplifying equipment at the apartment house H will result in the energization of the relay 94 and the opening of the low resistance shunt of the relay 68. When this shunt is open, the resistance in series with the relay 66 individual rto the trunk Th at the central -oilice A will be increased, and the relay 66 will be caused to fall off, thereby completing an alarm signal circuit 99 at the central office and fat the same time deenergizing the relay 62.- Relay 62 opens the low resistance shunt :for the relay 21VY of thetrunk Ta, thereby increasingY the resistance of the circuit of the marginal relay 20 at the main program station. TheY relay 20 thereupon releases its armature, opening,` the short circuit to the Winding of Vthe relay 97 whose lcircuitis now completed from ground, through its Winding, over the front contact and through the Winding kkof the relay 96, over the conductor 19, over the` Y contact of jack .L to battery.` Relay Y97, upon being energized, opens the circuit of the O. K. 'signal 13 at its left-hand contact and completes the circuit of the alarm or trouble signal 14 at its right-hand front contact.

The attendant at the main program station is thus informed that trouble has developed somewhere upon the circuit supplied by the trunk Ta. It there is no trouble man at the central 'ofiice A the attendant may then go to the central office A, and by determining which relay, such as 66, is decnergized will at once know that the trouble is local to the apartment house H. The attendant may then go to the apartment house H and make thc necessary repairs or adjustments.

At the central oflice A the equipment is so arranged that if one amplifying set becomes disabled by reason of the filament burning out or the plate circuit being' interrupted, a spare amplifier is switched into its l.place automatically. lt will be seen that since the filaments of the amplifiers A..l and A, are connected in series, if one filament Yburns out the plate current ceases to flow in all three tubes, Ythereby causing relays 54 and 57 to bc deenergized. A circuitis thereby completed `tor the relay 50 from ground, o-ver the back contact of the relay 46 of the power equipment, over conyductor 60, Yback contact of relay 57, front left-hand contact of relay 49, through the Winding of relay 50 to battery. It the plate A circuit. of the amplifier A4 is interrupted the relay 157 only will be deenergized. but the circuit of the relay 50 Will be completed in th(` same manner as just described. ln case thc plate circuit of amplifier Ay is interrupted, relay 54 only is deencrgizcd in which case the relay-50 is energized over a circuit previously traced to conductor 60 and thence llt) over the front contact of relay 57, back f contact of relay 54, front left-hand contact of relay 49, and through' the Winding of the relay 50 to battery. i

In any one of'these cases the relay 50 is energii/.ed and is locked up over a circuit from battery, over itsright-hand winding and over its right-hand front Contact, over the key 51, over the conductor 61 and over the right-hand front contact of relay 48 to ground. At its inner left-hand front contact relay 50'closesthe circuit of relay 52. Relay 52, upon-being energized, at its lefthand contactshifts the connection oi the filament battery from the filament circuits of the amplifiers AR and AA to the filament circuit' of the spare amplifying equipment ALJ-A4. The new circuit is as follows: from 24 Volt battery, left-hand front contact Learners:

of relay 52, through the choke coil and 'rersistance, and thence through the filaments.;` of amplifiers A4 and A3 1n serles to ground.

As soon as the filaments glow and the electron emisson starts. the space current in the tubes passes through the choke coil-53 and thence .in parallel through the relays 57 and 54 to the plates of the tubes of theampliiers A4 and An respectively.

The energization of relays 54 and 57 causes a circuit to be completed vfrom ground, over the front contact of relay 57', front contact of relay 54. and through the right-hand winding of relay 49 to battery. Relay 49 is locked up from battery, through its right-hand winding and over its right-hand front Contact, over the reset key 51, and thence to gro-und over the righthand front contact of relay 48. At its lefthand front contact relay 49 prepares a circuit for a trouble signal` .which circuit will be completed in case either or both of the relays 54 or 57 are deenergized. Consequently if any failure occurs either in the filament circuit or in the plate circuits of the amplifiers A3 and A4", thelocal trouble signal controlled by the relay 49 Will be operated.

Returning again. to relay 52, a circuit is completed from ground, over its inner righthand front contact, and throughy the Windings of relays99 and 100 to battery. The relays 99 and 100,'upon being energized, disconnect the terminals of the amplifying equipment A3 and A'4 from the trunk Ta and the conductors 15 and substitute the now operating amplifying equipment Alf-A4 instead. Returning to relay 50 the lefthand contact of said relay 50 completes a circuit for the local trouble signal 101, so

that if an attendant is on duty at thev cen? tra-l oflice he may locate the trouble and repair it.

At the same time it is desirable to give a signal at the main program station X. This is accomplished by having the circuit so arranged that Whenthe .rela-y 52 is energized to shift the amplifier connections its outer right-hand contact opens the low resistance shunt of the relay 21, this low resistance' shunt 'circuit being under the joint control of relays 49 and 52 of the amplifying equipment, relav 27 of the power equipment, and relay 62 individual to the outgoing trunk Th. Accordingly, the resistance in Iseries with the marginal relay 20 is increased when the amplifier connections are shifted, and the alarm signal 14 at the main program station will be actuated in a manner already described. i

Since. the amplifying equipment and power apparatus at. the central office A Will, in

, general, be located at a. central office of a v telephone system Where maintenance men are usually on duty, 'thelocal signals at-the from the main programV station.

central office will apprise such maintenance men of the trouble so that it may be taken care of without sending an attendant out Consequently the attendants at the main program station may disregard the alarm signal given at that station unless it continues for an unreasonable length of time. In the latter case the attendant at the main program station may communica-te with a maintenance man at the central ofiice, requesting him t-o look after the difiiculty, or if for somereason it cannot be taken care o-f at the central oflice someone may be sent from the main program station to loca-te the trouble.

Where the amplifying apparatus A1, and AAl has failed and the amplifying apparatus AR and A4 have been substituted therefor,

the trouble may be located and overcome by Well known methods. Usually the difiiculty will be that the filament of one of the Vacuum tubes has failed, and merely by inserting a new tube in the socket the amplifier circuit Will again Abe in good condition. Then it has been tested the trouble man will open the key 51, thereby opening the locking circuit of the relay 50. The initial energizing circuit of the relay 50 is held open over its outer left-hand front` contact. and consequently the relay 50 is deenergized When the key 51 is open. The deenergization of this relay Vopens the circ-uit of the relay 52atthe inner left-hand contact of the relay 50, so that the relay 52 releases its armature.v Accordingly the low resistance shunt 100 of the realy 21 is again closed at the outer right-hand contact of the relay The left,- hand contact of the relay 52 now opens the filament circuit of the amplifying equipment A ,-A4 and closes the filament circuit for the amplifying equipment Aas-A4 as previously described. Relay 52 also releases relays 99 and 100 to cut in thc amplifying equipment Agb-A1,.4 The apparatus will noW be in normal condition.

v If, While the amplifying equipment AH-A4 was out 4of service. the. amplifying equipment .AJ-A4 had also failed so that the signal 101 was actuated, the trouble man Would. after repairing the trouble in both amplifiers, actuate the reset key 51 as Well as the resetkey 51, thereby restoring the relay 49 to normal.

The manner in which the power equipment at the central office A functions when trouble develops will now be considered. Assuming that the switch PS is thro-Wn to its upper contact 25 so that. the'motorgenerator set-MG is running to supply the space current to the amplifiers as already described, it Will be remembered that under conductor G thereby preventing the relays- 54 and 47 (which will be released when the power fails) from closing the circuit of the relay 50. Consequently the relay 52 ot' the ampli-tying equipn'ient will not be energized to shii't the connection from one amplifier to the other merely because the power tails.

Relay 27, upon being energized, is locked up@ over a circuit from ground, over the outer front contact oi the relay 24, through the restore hey 45, and over the inner letthand front contact, and through the letthand winding ot relay 27 to battery. The middle lett-hand cont-act oi relay 27 opens the locl'ring circuit. oi the relay 42, permitting'v the latter relay to become decnergized, and closes a. looal signal circuit through the bell 102, through the restore key 105, and over the outer right-hand contact `ot relay 24 to ground. .At its outer left-hand contact relai/ 27 opens the low resistance shunt of Ithe relay 21 in the trunk circuit T, thereby causing the alarm signal 14 at the main program station to be actuated as already described.

At its right-hand contact relay 27 opens the circuit o"f the relay 29 (which it will be remembered was energized when the circuit Was yset vintovoperation with the switch PS on its upper contact 25). tion of relay 29 opens the circuit previously traced for relays 32 and 35, thereby causing the autostarter switch 33 to be released and the generator MG to be disconnected from the bus-bars 38. At the same time a circuit is closed for the power signa-l relay 32 from ground, over the inner front contact of relay.24, upper back contact of relay 29, control switch 31', and through the winding of relay 32' to battery. Relay 32 connects the electromagnet 33' of the autostarter switch to the power mains 34', thereby causing the switch to be actuated to conneet the operating circuit of the motor generator set MG' to the power mains 34'. The motor generator set MG' is accordingly set into operation. A circuit is also closed through the relay 35' from ground, over the inner front contact of relay 34, conductor 30, lower back contact of relay Iv29 and through the winding of relay 35 to battery. Relay 35' connects the output circuit of the motor generator set MG through the filter 37 to the bus-bars 38.

When this occurs and the motor generator set is in full operation, a generated voltage of 350 volts. will be supplied to the amplifier apparatus over the conductor 39., and' the relay 41 will be energized. This will cause the relay 42 to again be energized and locked up over circuits previously The deenergizatraced. The relay 42, upon releasing its left-hand armature, has previously opened the circuit recently traced for the relay 46 through the right-hand winding of the re- -lay 27. Relay 46, which is suiiiciently slow in releasing to permit the spare generator to be cut in, will'accordingly be dcenergized and will again connect ground to the conductor 60, so that if the amplifying apparatus A--A4 fails, the spare amplifier will be connected into the circuit. The relay 27, however, will remain locked up so that the signal 102 at the central voiiice will continue to be actuated, and the signal 14 at the main program station will also remain actuated.

A trouble man at the central oice A, if one is available, may, upon observing the signal 102, run down the trouble. If no trouble man is available at the central office A, the attendant at the main program station may, upon observing the signal 14, go to the central oiice A. to determine the cause of the diiculty. Upon determining that it is the generator MG which has developed trouble, the trouble manl may open the switch'PS, then actuate the restore key 45 to open the locking circuit of the relay 2'7 and thereafter connect the switch PS to the contact 25. The relay 27 upon being deenergized, willopen the circuit of the local sig! nal 102 and will close the low resistance shunt of the relay 21, so that the alarm signal 14 at the main program station will be restored to normal.

The generator may then be repaired, and

after i'tvhas been repaired the vspare generator MG' vmay be permitted to continue supplying the current so long as the switch PS is on its lower contact 25'. It, under these conditions, the motor generator MG' should develop trouble.. the relay 41 will be released. closing the circuits of relays 46 and 27. The latter opens the locking circuit of the relay 42 and restores it to normal, as already described, and at the same time shifts its right-hand contact so that the circuit for the relay 29 is closed from ground, over the inner front contact of relay 24, over the switch PS, contact 25', right-hand front contact of'rela-y 27, conductor 28, through the winding of relay 29 to battery. Relay 29, by shifting its upper and lower contacts to their front positions. thereby deenergizes power signal relay 32 'and relay 35'. Accordingly the .autostarter switch 33' is opened to disconnect the power from the motor generator MG', and the output of the generator is disconnected from the bus-bars. At the same time the circuits of the power signal rela-y 32 and the switching relay 35 are closed to set the motor generator MG into operation and'connect its output circuit to the bus-bars. Relay 41 then again pulls up its armature and the relay 42 is energized and locked up in the manlll ner aready described. Relay 46 in the meant me is deenergized to permit the automatic switching should fail. Relay 27 remains locked up so that the signal at the local central otlice and also thesignal at the main programstation will be given as before. The trouble may now be run 'dow'n in the manner already described in connection with the other motor generator. 4

It while the switch PS remained on its lower contact 25'., with the motor generator MG supplying the ampliiieiswhile the motor generator MG was repaired, it is desired to again cut in the motor generator MG after the repairs have been made, it is only necessary to shift the switch PS toits upper nects the motor ceases,

contact 25, the relay 27 having been restored by the restore key as already described.` A circuit will at once be closed from ground, over the inner yfront contact of relay 24, switch PS, contact 25, conductor 26, back right-hand contact of relay 27, conductor 28, through the winding of relay 29 to battery. Relay 29 attracts its armature, thereby stopp/[ilg and disconnecting the motor generator circuit to the bus-bars as already. described.

When the transmission from the studio the attendant at the program station may withdraw the idle plug from the jack J, and restore all of the apparatus to normal. The opening of the contact of the jack J, disconnects battery from the conductor 18 and thereby opens the filament circuit of the amplifiers A, and A2 at the pro-gram station. At the same time the circuit of the relay 96 is opened so that the O. K. signal 13 is restored to normal. rlhe circuit through the marginal relay 2O and the dis-` tant trunk relay 21 is opened, restoring both relays to normal. Relay 2l, upon being released, disconnects ground from conductor 22 thereby restoring relay 24 to normal. Relay 24, upon releasing its armature, opens the circuit of the relay 29 if the switch PS is on its upper contact 25 and disconnects ground from the circuits of power signal relay 32 and from relay 35.` The magnetic switch 33 is accordingly thus restored to normal thereby stopping the motor generator, and at the same time relay 35 discongenerator from the bus-bars. Returning again to relay 21, the disconnection of ground from conductor 22 releases relay 48, which in turn opens the filament circuit previously described for the ampliers A3 and A4 and at the same time disconnects the ground from conductor 61 to restore relay 49 to normal. Relay 48,

upon being released, also disconnects ground from conductor 63, thereby releasing the relay 64. Relay 64 in turn opens the circuits of the, relays, such as 66, of all of the of the ampliliers in case one that both relays are restored to normal. v

and at the same time starting the motor generator MG and connecting its output trunks connected to the bus-bars 16, therebyA releasing therelay 62. The relays, such 4as 68, of 'all of the-trunks are also released. Relay 68 disconnects ground from conductors 69 and 70 thereby opening the circuit of the relay 71, which in turn opens the circuitv of the power signal relay 72. The latter releases the automatic starter switch'73 so that the motor generator MG is stopped and the relays 78 and 82 released. The locking circuits of relays 7 9 and 83 were opened when the relay 71 was released, and the initial energizing circuits of these relays are opened by the relays 78 and 82, so

Disconnection of ground from conductor 69 by the relay 68 opens the circuit of relay 85, which in turn breaks the filament circuit of the amplifiers A5- and Au. The space 'current now ceases to flow so that relays 89 and 91 are restored to normal, thereby opening the circuit of the left-hand winding of relay 93. The circuit of the right-hand locking winding of said relay is opened by the disconnection of ground from conductor 84, so that this relay is restored to normal and the apparatus at the local distributing point is in its original condition.

It will be obvious that the general prin! ciples' herein disclosed may be embodied in manyother andv widely varied forms without departing from the spirit of the inven tion as defined in the appended claims.

What is claimed is: i

1.l In a distribution system, a main program station, trunks extending from said main station to outlying stations, ampli-v fying equipment associated with each trunk at the outlying station, and signaling means operated upon failure. of the amplifying equipment.

f 2. in a distribution system, a main program station, trunks extending from said main station to outlying stations, amplifying equipment associated with each trunk at the outlying station, and signaling means at the' main station operated upon failure of the amplifying equipment at an outlying station.

3. ln a distribution system, a main program station, trunks extending from said main station to outlying stations, amplitying equipment associated with each trunk at the outlying station, and signaling means at the main station corresponding to each trunk and means to operate the signal which corresponds to a given trunk at the main station upon failure of the amplifying equipment associated with that trunk.

4. ln a distribution system, a main program station, trunks extending from said main program station to a plurality of eutlying stations, two sets of amplifying equipment at each outlying station, one set being normally associated with the trunk, and

means to automatically connect the other amplifying equipment to the trunkv upon failure of said first mentioned equipment.

5. In a distribution system, a main program station, trunks extending `from said main program station to a plurality of outlying stations, two sets of amplifying equipment at each outlying station, one set being normally associated with the trunk, means to automatically connect the other amplifying equipment to the trunk upon failure of said first mentioned equipment, andwmeans to actua-te a signal when said first mentioned set of amplifying equipment fails.

6. In a distribution system, a main prograin station, trunks extending from saidV main program station to a plurality of outlying stations, two sets of amplifying equipment at each outlying station, one set being normally associated with the trunk, means tc automatically connect the other amplifying equipment to the trunk upon failure of said first mentioned equipment, and means to actuate a signal at the main station when said first mentioned set of amplifying equipment fails.

7. In a distribution system, a main programn station, trunks extending Vfrom .said main program station to outlying stations, translating apparatus associated with each trunk at the outlying station, power equipment at each outlying station for energizing said translating apparatus, and means to indicate failure of the power equipment..

. 8. In` a distribution system, a main pro-Y gram station, trunks extending from said main program station to outlying stations, translating apparatus associated with each trunk at the outlying station, power equipment at each outlying station for energizing said translating'apparatus, and means at the main stat-ion for indicating failure of the power equipment Vat an outlying stution.l

9. In a distribution system, a niain programfstation, trunks extending from said main program station to outlying stations, translating apparatus associated with each 'trunk at the outlying station, power equip- 12. YIn a distribution system, a inan pro-r gramstation, trunks extending from said main station to outlying stations, translating apparatus associated: with euch trunk, a source of energy for normally energizing said translating apparatus, a. spare source of energy, means for automatically associating the spare source with said translating apparatus upon failure of the normal source, and Ymeans at the central station to indicate failure of the normal source at an outlying station. Y

13. In a distribution system, a main programstation, trunks extending from said main station to outlying stations, amplifying apparatus at each outlying station, means to indicatefailure o-f the amplifying apparatus, power equipment for energizing said amplifyingapparatus, and means to indicate failure' of the power equipment.

:14. In a distribution system, a main pro-v gram'station, trunks extending from said main station to outlying stations. amplifying apparatus associated with each trunk at the outlying station, means at the central office to indicate failure of thc amplifying` apparatus at an outlying station, power equipment at each outlying station to energize the amplifying apparatus thereat, and means at the main station to indicate failure of the power equipment atan outlying station.

15. In a distribution system. a main program station, a plurality of trunks extending from said main station to outlying stations, aregular amplifying apparatus at each outlying station for the trunk extending thereto, a spare amplifying apparatus at eacli outlying station, means to disconnect the regular amplifying apparatus from `the trunk on the failure thereof and to connect to the trunk the spare amplifying apparatus, regular power equipment at each outlying oiiice for energizing the amplifiers tliereat, spare power equipment at each outlying station, and means to substitute the spare power equipment for the regular power equipment upon failure of the latter.

16. In a distribution system, a main proam station, a plurality ofl trunks extending from said main station to outlying sta- Y lying station,

tions, a regular amplifying apparatus at each outlying station for the trunk extending thereto, a spare amplifying apparatus at' each outlying station, means to disconnect the regular amplifying apparatus from the trunk on the failure thereof and to connectk to the trunk the spare amplifying'apparatus, regular power equipment at each out-v lying thereat, spare means to disconnect the regular amplifying apparatus from the trunk on the failure` thereof and to connect to the trunk tlie'spare amplifying apparatus, regular power equipment at each outlying office for energizing the amplifiers thereat, spare power equipment at each outlying station, means to substitute the spare power equipment for the regular power equipment upon failure of the latter, and means at the main station for indicating failure of the regular power equipment at an outlying station. i

18. ln a distribution system, a main pro gram station, a plurality of trunks extending from said main station to outlying stations, a regular amplifying apparatus at each outlying station for the trunk extending thereto, a spare amplifying apparatus at each outlying station, means to disconnect the regular amplifying apparatus from the trunk on the failure thereof and to' connect to theA trunk the spare amplifying apparatus, regular power equipment at each outlying office for energizing the amplifiers thereat, spare power equipment at each outlying station, lmeans to substitute the spare power equlp ment for the regular power equipment upon failure of the latter, and means to prevent the substitution of the spare amplifying equipment for the regular amplifying equipment upon failure of the regular power equipment.

19.In a distribution system, a main pro-- gram station, trunks extending from said main station to outlying stations, a normally inoperative amplifier associated with each trunk at the corresponding outlying station, and means to render said amplifiers operative fro-1n the main station.

20. In a distribution system, a main program station, trunks extending from said a spare amplifying apparatusmain stationto` outlying stations, a normally inoperative amplifier associated with each trunk' at the corresponding outlying station,

means to render said amplifiers operative from the'main station, and means at .the central office to indicate that the amplifiersA at the outlying stations are operative 21. In a'distribution system, a main program station, trunks extending` from said main station to outlying stations, translating apparatus at each outlying station, a normally in-active source of energy at each outlying station for energizing the translating apparatus thereat, and means to render said sources operative, from the main station.

22. In a distribution system, a main program station, trunks extending from saidmain station to outlying stations, translating apparatus lat each outlying station, 'a normally inactive source of energy at each outlying station for energizing the translating apparatus thereat, means to render said sources operative from the main station, and means at the main station for indicating that the sources are operating.

23. ln a distribution system, a main program station, trunks. extending from said main station to outlying stations. a normally inoperative amplifier associated with each trunk at the corresponding outlying station, a normally in-actiye source of energy at each station for energizing the amplifier thereat,

means for rendering the amplifiers at saidl outlying stations operative from said main station, and means to render said sources of energy active from said main station.

24. ln a distribution system, a main program station, trunks extending from said main station to outlying stations, a normally inoperativev amplifier associated with each trunk at the corresponding outlying station,

' a normally inactive source of energy at each station for energizing the amplifier thereat. means for rendering the amphfiers at said outlying statlons operative from sald main .statiom means to render said sources of energy active from said main station, and means at the-main station to indicate that all of the equipment at the outlying stations is operating.

25. in a distribution system, a main program station, trunks extending from said main station to central ofiices` ampliers for each trunk at 'each central office, trunks extending from each amplifier to distributing stations, amplifiers associated with each trunk at each distributing station, and means to indicate failure of any amplifier.

26. In a distribution system, a main program station, trunks extending fromsaid main station to central offices, ampliers for each trunk at each central office, trunks extending from each amplifier -to distributing stations, amplifiers associated with each gram station, trunks extending from said.

trunk l at each distributing station, and means at thc main program station for indicating failure of any outlying amplifier.

97. In a distribution system, a main progran'i station, trunks extending from said main station to central offices, translating apparatus for each trunk at cacli central oflice, power equipment at each central office for energizing the translating apparatus thereat, trunks extending from each central office to outlying distributing stations, trans-\ lating apparatus for each trunk at each distributing station, power equipment at each distributing station for energizing the translating apparatus thereat, and means to indicate failure of the power equipment at any outlying' point. i

28. In a distribution system, a main program station, trunks extending from said main station tocentral ofces, translating apparatus for each trunk at cach central office, power equipment at each central office for energizing the translating apparatus thereat, trunks extending from each central office to outlying distributing stations, translating apparatus for each trunk at each distributing station, power equipment at each distributing station for energizing the translating apparatus thereat, and means at the main program sta-tion to indicate failure of the power equipment at any outlying point.

29. In a distribution system, a main promain station to central offices, normally inoperative, amplifiers associated with each trunk at the corresponding central office, means to render said amplifiers operative from the main program station, trunks extending from each central ofce to distributing stations, normally inoperative amplifiers for each trunk at each distributing station, and means to render the amplifiers at the distributing stations operative from the main program station.

30. In a distribution system, a main program station, trunks extending from said main station to central offices, normally inoperative amplifiers associated with each trunk at the corresponding central ofiice, means to render said amplifiers' operative gram station, trunks extending from said main .station to central ofiices, translating apparatus for each trunk at each central ofice, a normally inactive source of energy at each central oflice to energize the translating apparatus thereat, means to render said sources active from the main program station, trunks extending from each central office to outlyingl distributing stations, translating apparatus associated with each trunk at each distributing station, a normally in-.

active source of energy at each distributing station for energizing the translating apparatus thereat, and means to render said.

sources active from the main program station.

32. In a distribution system, a main program station, trunks extending from said main station to central oices, translating apparatus for each trunk at each central office, a normally inactive source of energy at each central office to energize the transmitting apparatus thereat, means to render said sources active 'from the vmain program station, trunks extending from each central oflice to outlying distributing stations, translating apparatus associated With each trunk at each distributing station, a normally inactive source of energy at each distributing station for energizing the translating apparatus thereat, means to render said' sources active from the main program station, and means at the main program station `for indicating that all of the outlying sources of energy are operative.

y Intestimony whereof I have signed my name to this specification this 30th day of November, 1923.

JOHN F. TOOMEY. 

